How should I practice New-User Devices That Opened an App?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Microsoft onsite interview problems in FastPrep.

Is New-User Devices That Opened an App associated with Microsoft?

FastPrep tags this as a Microsoft onsite interview coding practice problem when the problem catalog has that company and stage context.

New-User Devices That Opened an App

Microsoft● EasyFULLTIMEONSITE INTERVIEW

Problem statement

Tables app_opens and device_users describe application activity and whether each known device belongs to a new user.

Return one row containing the number of distinct known new-user devices with at least one activity row whose open_count is positive.

Table schema

MySQLPostgreSQLPandas

Use the same input data with any supported language. Open the Schema tab in the editor to see the generated SQL setup or Pandas DataFrames.

app_opens

Column	Type	Nullable	Description
device_id	Text	No	—
app_name	Text	No	—
open_count	Integer	No	—

device_users

Column	Type	Nullable	Description
device_id	Text	No	—
is_new	Boolean	No	—

Expected result

Your query or function must return these columns.

Column	Type	Nullable	Description
new_device_count	Integer	No	—

Row order: must match exactly. Numeric tolerance: 0.

Constraints

A device can appear in multiple app_opens rows and must be counted once.
Rows with open_count = 0 do not qualify.
Activity for a device absent from device_users does not qualify.
Always return one row, including a zero count.